盐胁迫对嫁接西瓜幼苗生长及碳、氮、磷、钾化学计量特征的影响

Effects of salt stress on plant growth and stoichiometric characteristics of C,N,P and K of grafted watermelon seedlings

为探究抗枯萎病嫁接西瓜的盐适应性,获得抗枯萎病的耐盐组合,本研究基于1个自根苗京欣二号和2个嫁接苗[(Bj-6×893)+京欣二号]、[(Bj-9×341)+京欣二号],分析盐分胁迫对西瓜幼苗期叶片C、N、P、K含量及其元素计量比特征、光合特性和生物量累积的影响。结果表明:自根苗的根冠比、净光合速率和C∶N显著低于嫁接苗[(Bj-6×893)+京欣二号](9.6%、44.2%和15.5%)和[(Bj-9×341)+京欣二号](21.1%、30.1%和23.0%),而嫁接苗[(Bj-9×341)+京欣二号]的单株生物量、净光合速率、K含量和C∶P分别比嫁接苗[(Bj-6×893)+京欣二号]显著低9.7%、20.2%、70.3%和24.9%。与对照相比,盐胁迫分别使自根苗京欣二号和2个嫁接苗[(Bj-6×893)+京欣二号]、[(Bj-9×341)+京欣二号]的净光合速率显著下降60.3%、45.8%和41.9%,其C∶K显著下降48.2%、35.2%和59.4%,使叶片K含量显著增加44.8%、27.8%和56.8%;嫁接苗[(Bj-6×893)+京欣二号]、[(Bj-9×341)+京欣二号]的水分利用效率(WUE)在盐胁迫下显著提高33.5%和14.3%;盐分胁迫仅使嫁接苗[(Bj-9×341)+京欣二号]的C∶N和C∶P分别显著提高18.7%和15.5%,而对嫁接苗[(Bj-6×893)+京欣二号]影响不显著。基于以上结果和RDA分析表明自根苗京欣二号可能主要通过调节叶片K含量来缓解盐分胁迫,嫁接苗[(Bj-9×341)+京欣二号]和[(Bj-6×893)+京欣二号]可能通过提高叶片K含量和WUE来增强耐盐性,且嫁接苗[(Bj-6×893)+京欣二号]的耐盐性强于[(Bj-9×341)+京欣二号]。

In order to explore the salt adaptability of grafted watermelon with blight resistance and to obtain a combination of salt tolerance with blight tolerance,an experiment was conducted to investigate the effects of NaCl stress on biomass per plant,photosynthesis,water use efficiency(WUE),leaf stoichiometric characteristics among own-root seedling of Jingxinerhao and two grafted watermelon seedling[(Bj-6×893)+Jingxinerhao]and[(Bj-9×341)+Jingxinerhao].The findings showed that grafted watermelon seedlings had lower shoot-root ratio,photosynthesis,and C∶N ratio than those in[(Bj-6×893)+Jingxinerhao](9.6%,44.2%and 15.5%)and[(Bj-9×341)+Jingxinerhao](21.1%,30.1%and 23.0%).While biomass per plant,photosynthesis,potassium concentration and C∶P ratio in[(Bj-9×341)+Jingxinerhao]were significantly lower than those in[(Bj-6×893)+Jingxinerhao]by 9.7%,20.2%,70.3%,and 24.9%,respectively.Compared to control,salt stress significantly decreased photosynthesis(60.3%,45.8%and 41.9%)and C∶K ratio(48.2%,35.2%and 59.4%)in own-root seedling,[(Bj-6×893)+Jingxinerhao]and[(Bj-9×341)+Jingxinerhao],while significantly increased potassium concentration by 44.8%,27.8%,and 56.8%in the materials.The WUE significantly increased with salt addition by 33.5%and 14.3%in[(Bj-6×893)+Jingxinerhao]and[(Bj-9×341)+Jingxinerhao].Salt stress had significant positive effect on C∶N(18.7%)and C∶P(15.5%)in[(Bj-9×341)+Jingxinerhao].Based on above results and redundancy analysis,own-root seedling may improve its salt tolerance with increasing potassium concentration,while two grafted seedlings may simultaneously enhance WUE and potassium concentrations to improve their salt tolerance.The salt tolerance of grafted seedlings[(Bj-6×893)+Jingxinerhao]was greater than that of[(Bj-9×341)+Jingxinerhao].